Observations of the dynamics of ionic potassium-38 in brain

Short time course potassium dynamics in brain were investigated in the cat. 38K (T1/2 = 7.6m) was prepared on the BNL 60" cyclotron by the 40Ar(p, 3n)38K reaction. Positron decay in brain was measured by the limited angle of view positron camera (LAPC). Radioactivity corrected for physical decay following intravenous bolus injection of 38K showed an initial peak followed by a washout phase with a subsequent monotonic increase. The slope of the washout phase was linearly related to PaCO2 and the subsequent monotonic increase paralleled the arterial concentration of the tracer. No significant changes in 38K radioactivity were determined following coma producing levels of phenobarbital or seizure producing doses of potassium penicillin as compared to control.